Fickardt’s Patent Model of a Furnace – ca 1836

This model was filed with the application to the U.S. Patent Office for Patent Number 23 issued to Frederick A. Fickardt of Easton, Pennsylvania on September 8, 1836. His patent was for an improvement in furnaces for heating the upper rooms of a building. He claimed as new the use of an inner and outer chamber with insulating material on the outer chamber to reduce loss of heat into the furnace room. A gap of three to four inches was provided between the inner and outer chambers to further reduce loss of heat into the furnace room. The stove, or combustion chamber, was located within the inner chamber. Access to it for fueling and cleaning was via doors in both the inner and outer chambers. The inner chamber was open at the bottom allowing fresh air entry. The flue of the stove exited through this chamber via a sealed pipe. Heated air in the inner chamber was supplied to rooms above the furnace via a larger pipe, or duct, surrounding the flue of the stove. A sliding lid for the hot air duct was provided to stop cold or foul air entering the heated rooms from the cellar when the furnace was not in use. One of Fickardt’s claims was “Immediate heat, great heat, and economy of heat, and consequently economy of fuel, money, time, patience, and domestic comfort are the advantages which the subscriber hopes he is but reasonably led to anticipate by these improvements.” Research of available trade literature and other sources has not revealed any commercial use that may have made use of Mr. Fickardt’s invention.
The patent model is constructed of painted tinplate. The central stove can be seen through access doors in the inner and outer chambers. The stove flue and hot air ductwork are shown at the top of the model. The sliding lid for the hot air duct is also shown. Diagrams showing the complete design can be found in the patent document online ( The diagram submitted with the patent shows the shape of the furnace to be rectangular with a sloping top while the patent model submitted is cylindrical with a conical top.
Currently not on view
patent date
Fickardt, Frederick A.
associated place
United States: Pennsylvania, Easton
overall: 7 3/8 in x 3 3/8 in; 18.7325 cm x 8.5725 cm
ID Number
catalog number
accession number
patent number
Credit Line
Transfer from Department of the Interior
Patent Models
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Work and Industry: Mechanical and Civil Engineering
Patent Models
Engineering, Building, and Architecture
Data Source
National Museum of American History


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